U.S. Pat. No. 4,077,433 to Maldavs illustrates a piston valve arrangement with a passageway through the valve to assist in assuring that the male ball valve remains open in high flow conditions from the male to the female. U.S. Pat. No. 4,881,573 to Durant illustrates a coupler having two poppet valves. The first poppet engages a ball check valve formed in the male coupling and the second poppet is actuated by a manually operated cam. A passageway exists in the piston to allow fluid to be vented or to pressurize the female valve.
U.S. Pat. No. 4,598,896 to Maldavs illustrates a coupler having a spool and a port within the spool. An annular seal is fixedly positioned about the port in the spool. The spool is slidable with respect to the seal which enables pressure to be relieved in the female during coupling and uncoupling with the male. U.S. Pat. No. 4,303,098 to Shindelar discloses a coupler having a female half which includes a female valve having an elongated stem for engaging the male half. The female half of the coupling is vented by a pivotable cam which moves the inner member of the female half to release its locking means and then opens a poppet valve to open the outlet port.
U.S. Pat. No. 4,249,572 to Shindelar et al. discloses a female half which is self-relieving. The female half includes dual poppet valves which are linked together. One of the poppet valves vents the female half of the coupling when the male and female valves are disengaged and uncoupled.
International Publication WO 98/19097 published May 7, 1998 and filed Oct. 17, 1997 by applicant STUCCHI S. R. L. discloses a male half of the coupling in FIG. 1 thereof which includes a seal 40 carried in a fixed body 32, a piston 37, a safety valve 37 abutting an inner element 34, and, a relief valve 46 being a ball valve 46 actuated by pin 45 for venting to chamber 48. U.S. Pat. No. 5,592,970 to Stucchi et al. issued Jan. 14, 1997 discloses structure similar to WO 98/19097 except the relief valve and pin are missing. The '970 patent is directed to preventing the blowout of seal 40 by covering it with bush 10.
The structure disclosed in WO 98/19097 will leak by the ball valve 46 and the interface between valve 73 and inner body member 34 at low pressures, for example, below 500 psig. Leaking around valve 46 and the interface negates the purpose of the relief valve 46 as the volume available will be filled. Leakage may occur at pressures greater than 500 psig but the increased pressures tend to enhance the metal to metal seals employed by STUCCHI S. R. L. in WO 98/19097.
U.S. Pat. No. 3,498,324 to Breuning discloses secondary valves which first engage each other and open causing a flow through the secondary flow passages from the high pressure side to the low pressure side of the coupling.
U.S. Pat. No. 5,159,955 to Ekman discloses a pressure reducing and bleed means located between two chambers 25 and 26 in a coupling half.
U.S. patent application Ser. No. 09/020,447 to applicant Dennis Zeiber, assigned to Snap-Tite Technologies, Inc. discloses and claims a relief valve positioning member in the female half which includes a relief valve to enable easy coupling when the female member is pressurized. U.S. patent application Ser. No. 09/037,461, a continuation-in-part of Ser. No. 09/020,447 just mentioned discloses and claims a relief valve engaging the body of the female valve.
U.S. Pat. Nos. 5,063,965 and 5,072,755 both to Wilcox and assigned to Snap-Tite Technologies, Inc. disclose balanced couplings employing metal seals. U.S. Pat. No. 5,730,185 to Wilkins et al. and assigned to Snap-Tite Technologies, Inc. discloses the connection of a dispenser half to a receptacle half by an operator using a single hand. Similarly, the dispenser half may be disconnected from the receptacle half using a single hand. Disconnection requires first that the pressure in the dispenser half be vented to an accumulator which permits the unlocking of the dispenser half from the receptacle half. Next the dispenser half is separated from the receptacle half by the operator using a single hand.
U.S. Pat. Nos. 5,415,440 and 5,664,832 to Kanao et al. disclose a t-shaped seal material which fits in troughs of spiral pipe as shown in FIG. 6 of either patent. U.S. Pat. No. 5,429,553 to Schoeps discloses t-shaped seal members 12, 13 for use in a hydraulic motor. U.S. Pat. No. 4,533,115 to Lissau discloses a t-shaped seal 38 for use in gladhand coupling applications.
None of the related art, however, discloses a female coupling half which vents into the male half during coupling, protects the seals in the male half of the coupling, and is substantially pressure balanced. Nor does any of the related art disclose a male half of the coupling which vents by way of a series of passageways and an aperture in a ball housing so as to protect the seals in the male half of the coupling during engagement with the female half of the coupling.